Principal Mechanical Engineer - Commercial HVAC

Who We Are Lennox (NYSE: LII) Driven by 130 years of legacy, HVAC and refrigeration success, Lennox provides our residential and commercial customers with industry-leading climate-control solutions. At Lennox, we win as a team, aiming for excellence and delivering innovative, sustainable products and services. Our culture guides us and creates a workplace where all employees feel heard and welcomed. Lennox is a global community that values each team member’s contributions and offers a supportive environment for career development. Come, stay, and grow with us. What Drives Success Innovate your career. When you choose Lennox, you're getting the best. When you work at Lennox, you’re among the best. As a leading innovator of home and commercial, heating, cooling, refrigeration, air-quality, and related services, Lennox is committed to helping our people innovate our products and their careers. This Principal Engineer will develop and apply advanced mechanical engineering methods, theories, and research techniques to solve complex technical challenges related to Heat Transfer, Thermodynamics, and HVAC systems , with a strong emphasis on Commercial Rooftop Air Conditioners (RTUs) and Unitary HVAC equipment . DUTIES INCLUDE, BUT ARE NOT LIMITED TO: Lead analysis, system design, and performance validation activities for commercial rooftop air conditioning systems , focusing on efficiency, reliability, manufacturability, and regulatory compliance. Use advanced mechanical engineering design tools to develop technical plans, blueprints, drawings, and models for HVAC product development. Conduct investigations and testing activities of significant complexity to support new product development, system enhancements, and validation of applied design methods. Responsible for design and optimization of heat exchangers, refrigeration circuits, and airflow pathways used in commercial HVAC systems. Review industry literature, standards, patents, and competitive products to ensure designs follow best practices and emerging technologies. Recommend improvements or corrections to technical analyses, design approaches, and engineering methodologies. Evaluate vendor capabilities and components to ensure alignment with product performance and quality requirements. Provide technical guidance, mentorship, and consultation to cross‑functional teams and junior engineers. Plan, lead, and technically direct engineering projects or major project phases, coordinating efforts across engineering and technical support staff. ADDITIONAL RESPONSIBILITIES: Develop and execute test plans for commercial unitary heat pump systems , including heating performance, defrost operation, compressor cycling, refrigerant charge optimization, and low‑ambient operation. Analyze test data to validate performance against DOE efficiency standards, AHRI testing requirements, and internal performance targets. Support development of improved HVAC technologies, including evaluating new heat transfer surfaces and improved compressor technologies like variable speed and tandem compressors. Collaborate with laboratory teams to configure test setups, instrumentation, psychrometric environments, and load conditions to ensure accurate and repeatable results. Document findings and recommend design changes based on test outcomes. Support Development of engineering samples, field trials, pilot and start of production activities at remote manufacturing facilities. #LI-JM1 #LI-onsite What We Are Looking For Bachelor's degree in Mechanical Engineering (Master's degree preferred) followed by 10 years of progressive experience in an engineering position/occupation. 15+ years of overall experience involving Heat Transfer, Thermodynamics, HVAC systems analysis, system design, and performance validation. Expert understanding of the practical application of engineering science and technology. Experience with analytical and CAD software. Requires expert knowledge of design techniques, tools, and principles involved in production of precision technical plans, blueprints, drawings, and models. Excellent verbal and written communication and presentation skills. What We Offer Compensation : This is a salaried exempt role. The starting salary range for this role and market is between $142,000 - $160,000 annually. Factors that may affect starting salary include geography/market and the skills, education, experience, and other qualifications of the successful candidate. Employees in this role are also eligible for an annual bonus in accordance with the terms of the Company’s applicable plan. Employees in this role are not eligible for overtime. Location and Schedule : This position is located in Carrollton, TX and will be in the office Monday through Friday. Benefits : Subject to applicable eligibility requirements, the following benefits are offered for this role: tuition reimbursement; medical, dental, and vision insurance; prescription drug coverage; 401(k) retirement plan; short-term disability insurance; 8 weeks paid birthing leave; 2 weeks paid bonding leave; life and long-term disability insurance. Paid Time Off: Depending on date of hire, and subject to applicable eligibility requirements, new employees in this role also receive up to: 12 days paid time off, 2 paid well-being days, 1 paid volunteer day, 9 to 11 paid company holidays depending on the year, and 3 floating holidays per year. Our Culture : At Lennox, our Core Values of Integrity, Respect & Excellence are ingrained in the fabric of the organization. They define our culture – which is about how we do business and how we treat others. Lennox is not just a workplace; we are a global community that values each team member’s contributions. As an equal opportunity employer, we are committed to recruit, develop, and retain talented individuals from a wide range of backgrounds, ensuring that everyone has the opportunity to succeed and contribute to our continued growth and success. At Lennox, you’ll take pride in our brands, knowing you are part of something special. Come, stay, and grow with us! Disclaimers:The compensation and benefits information is accurate as of the date of this posting. Lennox reserves the right to modify this information at any time, with or without notice, subject to applicable law. #J-18808-Ljbffr